Mobile robot and method for controlling same

ABSTRACT

The present invention relates to a mobile robot and a method for controlling the same. The present invention provides a mobile robot using the rotational force of at least three rotating members as a movement power source and a method for controlling the same, in which the mobile robot is controlled to effectively travel along a set curved driving path and not deviate from the set curved driving path, or to immediately return to the curved driving path when deviating from the set curved driving path.

TECHNICAL FIELD

The present invention relates to a mobile robot, and more particularly,to a mobile robot traveling autonomously by including at least threerotating members, and a method for controlling the same.

BACKGROUND ART

Due to a recent technological development, there is not only a rapiddevelopment in technology of a mobile robot, but also very diverseutilizations and applications of the mobile robot. A representativeexample may be a robot cleaner which may perform cleaning whiletraveling autonomously without a user's manual operation.

A related market spotlights a robot cleaner which may use a rotationalforce of a rotating member to which a wet and/or dry cleaner (e.g., mop)is attached as its movement power source without wheels among variousrobot cleaners.

This robot cleaner may remove a foreign material or ingrained dirtadhered to a floor surface better than a robot cleaner traveling usingwheels because this cleaner exerts more adhesive and frictional forceson the floor surface (i.e., surface to be cleaned).

However, the conventional robot cleaner using the rotational force ofthe rotating member may generally have two rotating members, and thefloor surface existing between the two rotating members may be oftenexcluded from its cleaning region.

Therefore, the conventional robot cleaner using the rotational force ofthe rotating members may have superior cleaning power than the robotcleaner traveling using wheels, and still have a technical limitation inguaranteeing perfect cleaning power.

A study has been conducted on a robot cleaner using at least threerotating members as a part of an effort to overcome the above technicallimitation. For example, a robot mop cleaner is disclosed in KoreanPatent No. 10-1966083 (application number: 10-2017-0156226).

However, as two rotating members are changed to at least three rotatingmembers, it may be more difficult to control smooth travel of the mobilerobot. Therefore, there is a constant need to control the mobile robotmore precisely.

DISCLOSURE Technical Problem

An object of the present invention is to provide a mobile robot usingrotational forces of at least three rotating members as its movementpower sources to travel smoothly along a set travel path, and a methodfor controlling the same.

Another object of the present invention is to provide a mobile robotincluding at least three rotating members and capable of effectivelycontrolling the at least three rotating members to travel a set curvedtravel path when performing curved travel, and a method for controllingthe same.

Yet another object of the present invention is to provide a mobile robotincluding at least three rotating members and capable of effectivelycontrolling the at least three rotating members to return to a setcurved travel path or not to deviate from the curved travel path in acase where the robot deviates from the set curved travel path whenperforming a curved travel, and a method for controlling the same.

Still another object of the present invention is to provide a mobilerobot having various technical means to maintain the above-mentionedcurved travel path, and a method for controlling the same.

Technical Solution

In one general aspect, a mobile robot includes: a main body; a drivingunit installed on the main body and supplying power for travel of themobile robot; a first rotating member, a second rotating member and athird rotating member, capable of accommodating respective cleaners andproviding movement power sources for the travel of the mobile robot byperforming respective rotational motions about a first rotation axis, asecond rotation axis and a third rotation axis by power of the drivingunit; and a control unit controlling the driving unit for the firstrotating member and the second rotating member to rotate at differentspeeds in opposite directions and for the third rotating member torotate in the same direction as a rotation direction of a rotatingmember having a higher speed among the first rotating member and thesecond rotating member, wherein the first rotation axis corresponding tothe first rotating member and the second rotation axis corresponding tothe second rotating member are each inclined to have a predeterminedangle with respect to a central axis, corresponding to a vertical axisof the mobile robot, for the first rotating member and the secondrotating member to each have an angle with the ground, and the thirdrotation axis corresponding to the third rotating member is parallel tothe central axis for the third rotating member to be parallel to theground.

In addition, the first, second and third rotation axes may be formed forthe first, second and third rotating members to be disposed adjacent toone another.

In addition, the control unit may control the driving unit for the thirdrotating member to rotate at a lower speed than the rotating memberhaving a higher speed and for a rotational speed of the third rotatingmember to have a value of 10% or more of a rotational speed of therotating member having a higher speed.

In addition, the control unit may control the rotational speed of atleast one of the first, second and third rotating members for the mobilerobot to maintain a preset curved travel direction or travel angle withrespect to a forward or backward direction during the travel of themobile robot.

In addition, the mobile robot may further include a detection unitcapable of detecting the preset curved travel direction or travel angle.

Here, the control unit may control the rotational speed of at least oneof the first, second and third rotating members for a travel directionof the mobile robot to maintain the preset travel direction or travelangle based on a signal of the detection unit in a case where the traveldirection of the mobile robot deviates from the preset curved traveldirection or travel angle.

In addition, the detection unit may include at least one of anacceleration sensor and a gyro sensor.

In addition, the control unit may control the rotational speed of atleast one of the first, second and third rotating members inconsideration of at least one of a friction level of a floor surface onwhich the mobile robot travels and whether the cleaner is wet or dryduring the travel of the mobile robot.

In addition, the control unit may determine the friction levels of thefloor surface corresponding to the first rotating member and the floorsurface corresponding to the second rotating member by obtaining a firstload value applied to the first rotating member and a second load valueapplied to the second rotating member.

In addition, the control unit may control the rotational speed of atleast one of the first rotating member and the second rotating member inconsideration of the first load value and the second load value for themobile robot to maintain a preset curved travel direction or travelangle with respect to a forward or backward direction.

In addition, the control unit may determine whether the cleaner is wetor dry by any one of a signal received from an external remotecontroller and detection of a predetermined color corresponding to eachof the wet cleaner and the dry cleaner.

In another general aspect of the present invention, a method forcontrolling a mobile robot using rotational forces of a plurality ofrotating members as movement power sources for its travel, includes:allowing a mobile robot to travel by rotating at least one of a firstrotating member, a second rotating member and a third rotating member,capable of accommodating respective cleaners and performing respectiverotational motions about a first rotation axis, a second rotation axisand a third rotation axis; and controlling the first, second and thirdrotating members for the first rotating member and the second rotatingmember to rotate at different speeds in opposite directions and for thethird rotating member to rotate in the same direction as a rotationdirection of a rotating member having a higher speed among the firstrotating member and the second rotating member, wherein the firstrotation axis corresponding to the first rotating member and the secondrotation axis corresponding to the second rotating member are eachinclined to have a predetermined angle with respect to a central axis,corresponding to a vertical axis of the mobile robot, for the firstrotating member and the second rotating member to each have an anglewith the ground, and the third rotation axis corresponding to the thirdrotating member is parallel to the central axis for the third rotatingmember to be parallel to the ground.

In addition, the first, second and third rotating members may bedisposed adjacent to one another.

In addition, the controlling may include controlling at least one of thefirst, second and third rotating members for the third rotating memberto rotate at a lower speed than the rotating member having a higherspeed and for a rotational speed of the third rotating member to have avalue of 10% or more of a rotational speed of the rotating member havinga higher speed.

In addition, the method for controlling a mobile robot may furtherinclude controlling the rotational speed of at least one of the first,second and third rotating members for the mobile robot to maintain apreset curved travel direction or travel angle with respect to a forwardor backward direction during the travel of the mobile robot.

In addition, the method for controlling a mobile robot may furtherinclude: obtaining a first load value applied to the first rotatingmember and a second load value applied to the second rotating memberduring the travel of the mobile robot; and controlling the rotationalspeed of at least one of the first rotating member and the secondrotating member in consideration of the first load value and the secondload value for the mobile robot to maintain a preset curved traveldirection or travel angle with respect to a forward direction.

In addition, the controlling may include controlling the rotationalspeed of at least one of the first, second and third rotating members inconsideration of at least one of a friction level of a floor surface onwhich the mobile robot travels and whether the cleaner is wet or dryduring the travel of the mobile robot.

In yet another general aspect, a computer program stored in a medium maybe provided to execute the method of the present invention.

In still another general aspect, a distribution server for distributingthe computer program stored in a medium may be provided to execute themethod of the present invention.

Advantageous Effects

The mobile robot and the method for controlling the same according tothe present invention may provide the following effects.

According to the present invention, the mobile robot using therotational forces of at least three rotating members as its movementpower sources may travel smoothly along the set travel path.

In addition, according to the present invention, the mobile robot maytravel effectively along the set curved travel path when performing thecurved travel by including at least three rotating members.

In addition, according to the present invention, the mobile robotincluding at least three rotating members may return to the set curvedtravel path or not to deviate from the curved travel path in the casewhere the robot deviates from or is about to deviate from the set curvedtravel path when performing the curved travel.

In addition, according to the present invention, the mobile robotincluding at least three rotating members may have various technicalmeans to maintain the above-mentioned curved travel path, and may thustravel the set curved travel path efficiently and effectively.

However, the scope of the present invention is not limited to theabove-described effects.

DESCRIPTION OF DRAWINGS

FIG. 1 is a view showing an exterior of a robot cleaner as an example ofa mobile robot to which the present invention is applied.

FIG. 2 is a block diagram of the mobile robot according to an embodimentof the present invention.

FIG. 3 is a view showing an example of a driving unit.

FIG. 4 is a front view of the mobile robot according to an embodiment ofthe present invention.

FIG. 5 is a cross-sectional view of the mobile robot according to anembodiment of the present invention.

FIG. 6 is a flowchart showing a method for controlling a mobile robotaccording to another embodiment of the present invention.

FIG. 7 is a view showing an example in which the mobile robot movesforward to the left along a curved path according to another embodimentof the present invention.

FIG. 8 is a view showing an example in which the mobile robot movesforward to the right along the curved path according to anotherembodiment of the present invention.

FIG. 9 is a view showing an example in which the mobile robot movesbackward to the right along the curved path according to anotherembodiment of the present invention.

FIG. 10 is a view showing an example in which the mobile robot movesbackward to the left along the curved path according to anotherembodiment of the present invention.

FIG. 11 is a flowchart showing a method for controlling a mobile robotaccording to yet another embodiment of the present invention.

FIG. 12 is a flowchart showing a method for controlling a mobile robotaccording to still another embodiment of the present invention.

BEST MODE

Information on the operational effect and technical configuration of amobile robot and a method for controlling the same according to thepresent invention to achieve the above objects will be clearlyunderstood by the following detailed description with reference to thedrawings showing preferred embodiments of the present invention.

The following merely exemplifies a principle of the present invention.Therefore, those skilled in the art may implement the principle of thepresent invention and invent various devices included in the spirit andscope of the present invention although not clearly described or shownin the present specification. In addition, it is to be understood thatall conditional terms and embodiments mentioned in the presentspecification are obviously intended only to assist in understanding aconcept of the present invention in principle, and the present inventionis not limited to embodiments and states particularly mentioned as such.

Further, it is to be understood that all detailed descriptionsmentioning specific embodiments of the present invention as well asprinciples, aspects, and embodiments of the present invention areintended to include structural and functional equivalences thereof.Further, it is to be understood that these equivalences include anequivalence that will be developed in the future as well as anequivalence that is currently well-known, that is, all elements inventedso as to perform the same function regardless of a structure.

Further, when it is determined that a detailed description of the knownart related to the present invention may obscure the gist of the presentinvention, the detailed description thereof will be omitted.Additionally, components in the drawings are not necessarily drawn toscale.

For example, sizes of some of the components in the drawings may beexaggerated as compared with other components in order to assist in theunderstanding of embodiments of the present invention. In addition, thesame reference numerals in different drawings denote the samecomponents, and similar reference numerals denote similar components,although not necessarily.

Therefore, it is to be understood that, for example, block diagrams ofthe present specification illustrate a conceptual aspect of anillustrative circuit for embodying the principle of the presentinvention. Similarly, it is to be understood that all flow charts, statetransition diagrams, pseudo-codes and the like, illustrate variousprocesses that may be tangibly embodied in a computer readable mediumand that are executed by computers or processors regardless of whetheror not the computers or the processors are clearly illustrated.

Functions of various elements including processors or functional blocksrepresented as concepts similar to the processors and illustrated in thedrawings may be provided using hardware having capability to executeappropriate software as well as dedicated hardware. When provided by theprocessors, the functions may be provided by a single dedicatedprocessor, a single shared processor or a plurality of individualprocessors, and some of the processors may be shared with each other.

Further, explicit use of terms presented as processors, controls, orsimilar concepts should not be construed as exclusively referring tohardware capable of executing software, and may implicitly include,without limitation, digital signal processor (DSP) hardware, a read-onlymemory (ROM), a random access memory (RAM) and a non-volatile memory,for storing the software. The above-mentioned terms may also includewell-known other hardware.

In the claims of the present specification, components represented asmeans for performing functions mentioned in the detailed description areintended to include all methods for performing functions including alltypes of software including, for example, a combination of circuitelements performing these functions, firmware/micro codes or the like,and are coupled to appropriate circuits for executing the software so asto execute these functions. It is to be understood that functionsprovided by variously mentioned means are combined with each other andare combined with a method demanded by the claims in the presentinvention defined by the claims, and any means capable of providingthese functions are thus equivalent to means recognized from the presentspecification.

The above-mentioned objects, features and advantages will become moreobvious from the following detailed description associated with theaccompanying drawings. Therefore, those skilled in the art to which thepresent invention pertains may easily practice a technical idea of thepresent invention.

Hereinafter, various embodiments according to the technical idea of thepresent invention will be described in detail with reference to theaccompanying drawings.

The present specification mainly describes a robot cleaner as an exampleof the mobile robot to which the present invention is applied. However,it is obvious that the mobile robot to which the present invention isapplied is not limited to the robot cleaner.

FIG. 1 is a view showing an exterior of a robot cleaner as an example ofa mobile robot to which the present invention is applied; and FIG. 2 isa block diagram of the mobile robot according to an embodiment of thepresent invention.

Referring to FIGS. 1 and 2 , a mobile robot 10 according to anembodiment of the present invention may include a main body 11 formingan exterior of the mobile robot 10, a driving unit 110 installed on themain body 11 and supplying power for travel of the mobile robot 10, afirst rotating member 12 a, a second rotating member 12 b and a thirdrotating member 12 c, coupled to the driving unit 110 to performrespective rotational motions, and a power supply unit 120 installed inthe main body 11.

The mobile robot 10 according to an embodiment of the present inventionmay travel while performing dry or wet cleaning by using a first cleaner13 a, a second cleaner 13 b and a third cleaner 13 c.

Here, the cleaning may refer to an operation of wiping a surface to becleaned using the cleaners 13 a, 13 b and 13 c. The dry cleaning mayinclude cleaning using a dry rag or the like and the wet cleaning mayinclude cleaning using a rag wet with liquid.

The first cleaner 13 a, the second cleaner 13 b and the third cleaner 13c may respectively be accommodated in the first rotating member 12 a,the second rotating member 12 b and the third rotating member 12 c.

The first cleaner 13 a, the second cleaner 13 b and the third cleaner 13c may respectively be detachably attached to the first rotating member12 a, the second rotating member 12 b and the third rotating member 12c.

The first, second and third rotating members 12 a, 12 b and 12 c may bedisposed adjacent to each other, and a triangle may be formed whenconnecting respective center points of the first, second and thirdrotating members 12 a, 12 b and 12 c one another.

The driving unit 110 may include a first driving unit 110 a installed inthe main body 11 and coupled to the first rotating member 12 a, a seconddriving unit 110 b installed in the main body 11 and coupled to thesecond rotating member 12 b, and a third driving unit 110 c installed inthe main body 11 and coupled to the third rotating member 12 c.

In addition, the driving unit 110 may be implemented including a motor,a gear assembly and the like. FIG. 3 is a view showing an example of thedriving unit.

The first rotating member 12 a may be coupled to the first driving unit110 a and include a first transmitting member (not shown) transmittingpower of the first driving unit 110 a and performing the rotationalmotion about a first rotation axis by the power, and a first fixingmember (not shown) to which the first cleaner 13 a may be fixed.

In addition, the second rotating member 12 b may include a secondtransmitting member (not shown) coupled to the second driving unit 110 bto transmit power of the second driving unit 110 b and performing therotational motion about a second rotation axis by the power, and asecond fixing member (not shown) to which the second cleaner 13 b may befixed.

In addition, the third rotating member 12 c may include a thirdtransmitting member (not shown) coupled to the third driving unit 110 cto transmit power of the third driving unit 110 c and performing therotational motion about a third rotation axis by the power, and a thirdfixing member (not shown) to which the third cleaner 13 c may be fixed.

The first cleaner 13 a, the second cleaner 13 b and the third cleaner(13 c) may be made of a fibrous material such as a cloth capable ofwiping various surfaces to be cleaned, for example, a micro-fiber cloth,a rag, a non-woven fabric or a brush, in order to remove a foreignmaterial adhered to a floor surface by performing the rotational motion.

In addition, the first cleaner 13 a, the second cleaner 13 b and thethird cleaner 13 c may each have a circular shape, and may beimplemented in various shapes without limitation in shape.

The mobile robot 10 according to an embodiment of the present inventionmay remove the foreign material adhered to the floor through frictionwith the surface to be cleaned as the cleaners 13 a, 13 b and 13 crotate by the rotational motions of the first, second and third rotatingmembers 12 a, 12 b and 12 c. In addition, when a frictional force isgenerated between the cleaners 13 a, 13 b and 13 c and the surface to becleaned, the frictional force may be used as a movement power source ofthe mobile robot 10.

For example, in the mobile robot 10 according to an embodiment of thepresent invention, as the first, second and third rotating members 12 a,12 b and 12 c rotate, the frictional force may be generated between thecleaners 13 a, 13 b and 13 c and the surface to be cleaned, and thetravel speed and travel direction of the mobile robot 10 may bedetermined based on the magnitude and direction of its resultant force.

In addition, for example, in the mobile robot 10 according to anembodiment of the present invention, as the first and second rotatingmembers 12 a and 12 b rotate, the frictional force may be generatedbetween the cleaners 13 a and 13 b and the surface to be cleaned, andthe travel speed and travel direction of the mobile robot 10 may bedetermined based on the magnitude and direction of its resultant force.

Here, rotations of the first and second rotating members 12 a and 12 bmay determine the travel speed and travel direction of the mobile robot10, and rotation of the third rotating member 12 c may act as asupplement without affecting the travel speed and travel direction ofthe mobile robot 10 based on its speed.

Referring to FIG. 2 , the mobile robot 10 according to an embodiment ofthe present invention may include the driving unit 110, the rotatingmembers 12 a, 12 b and 12 c, the power supply unit 120, an input unit130, an obstacle detection unit 140, a load detection unit 150, adirection detection unit 151, a communication unit 160, an output unit170, a storage unit 180 and a control unit 190.

The power supply unit 120 may supply power to the mobile robot 10. Indetail, the power supply unit 120 may supply power to each functionalunit included in the mobile robot 10, and may be charged by receiving acharging current when a remaining amount of power is insufficient. Here,the power supply unit 120 may be implemented as a rechargeable battery.

The input unit 130 may receive a user input for operating the mobilerobot 10. In particular, the input unit 130 may receive a user input forselecting a cleaning mode of the mobile robot 10. Here, the cleaningmode may include an intensive cleaning mode for intensively cleaning asurrounding space based on a current position of the mobile robot 10, awall-along cleaning mode for performing the cleaning while travelingalong a wall, a manual cleaning mode for performing the cleaning whiletraveling in a direction corresponding to a user direction-key inputvalue, a S-shaped cleaning mode for performing the cleaning whiletraveling in an S-shaped pattern, a Y-shaped cleaning mode forperforming the cleaning while traveling in a Y-shaped pattern, astraight cleaning mode for performing the cleaning while traveling in astraight line, an automatic cleaning mode for performing the cleaning byautomatically selecting a cleaning mode suitable for a travel situationof the mobile robot 10 among the plurality of cleaning modes, etc.

The obstacle detection unit 140 may detect various objects andobstacles, such as a fixed object such as furniture, a wall or astructure, or a moving object such as a person or an animal. Theobstacle detection unit 140 may be implemented as various means such asan infrared sensor, a laser, a collision detection means or the like.

In addition, the obstacle detection unit 140 implemented as the variousmeans described above may detect various obstacles that interfere withthe travel of the mobile robot 10, such as low obstacles such asthresholds and carpets, obstacles floating above a certain height suchas sofas or beds, high obstacles such as walls, and obstacles such asfalling points.

The load detection unit 150 may obtain a load value each applied to thefirst, second and third rotating members 12 a, 12 b and 12 c. In detail,the load detection unit 150 may obtain the load value each applied tothe first, second and third rotating members 12 a, 12 b and 12 c byusing a load current applied to a motor.

For example, the load detection unit 150 may detect the load eachapplied to the first, second and third rotating members 12 a, 12 b and12 c based on the travel of the mobile robot 10.

For example, during the travel of the mobile robot 10, a large load mayoccur in the first rotating member 12 a to which the first cleaner 13 ais attached when the first cleaner 13 a comes into contact with aforeign material such as ingrained dirt positioned on the surface to becleaned or water.

For another example, during the travel of the mobile robot 10, a largeload may occur in the second rotating member 12 b to which the secondcleaner 13 b is attached when the second cleaner 13 b comes into contactwith the foreign material such as the ingrained dirt positioned on thesurface to be cleaned or water.

That is, in order to respond to various environments of the surface tobe cleaned, which may occur during the travel of the mobile robot 10,the load detection unit 150 may detect the load each applied to thefirst, second and third rotating members 12 a, 12 b and 12 c based onthe travel of the mobile robot 10.

The load detection unit 150 may include a first load detection unitobtaining a first load value applied to the first rotating member 12 a,a second load detection unit obtaining a second load value applied tothe second rotating member 12 b, and a third load detection unitobtaining a third load value applied to the third rotating member 12 c.

Here, the first load value may be a load current value of a first motorproviding a driving force for driving the first rotating member 12 a,the second load value may be a load current value of a second motorproviding a driving force for driving the second rotating member 12 b,and the third load value may be a load current value of a third motorproviding a driving force for driving the third rotating member 12 c.That is, the load detection unit 150 may be implemented as a means fordetecting the load current value of the motor.

However, this configuration is only an embodiment of the presentinvention, and the load detection unit 150 may calculate theabove-described load value by using data other than the load currentvalue applied to the motor.

In more detail, according to another embodiment of the presentinvention, the load detection unit 150 may calculate the above-describedload value by comparing a difference between rotational speeds of thefirst and second rotating members 12 a and 12 b, requested based on acontrol signal of the control unit 190, and actually-output rotationalspeeds of the first and second rotating members 12 a and 12 b.

The direction detection unit 151 may detect the travel direction of themobile robot 10, a travel angle of the mobile robot 10, whether themobile robot 10 performs a straight travel, etc. In more detail, thedirection detection unit 151 may be implemented as a three-axisacceleration sensor or a six-axis sensor (i.e. a three-axis accelerationand three-axis gyro sensor), and is not limited thereto.

Here, the travel angle of the mobile robot 10 may indicate an angleformed when the mobile robot 10 travels along a curved path such asforward left, forward right, backward left or backward right.

In addition, straight travel of the mobile robot 10 may include forwardtravel along a straight path and backward travel along the straightpath.

The communication unit 160 may include at least one module that enableswireless communication between the mobile robot 10 and another wirelessterminal or between the mobile robot 10 and a network in which anotherwireless terminal is positioned. For example, the communicating unit 160may communicate with the wireless terminal, which is a remotecontroller, and may include a short-range communication module or awireless internet module, for this purpose.

The output unit 170 is to generate an output related to a visual sense,an auditory sense or the like, and may include a display unit, a soundoutput module, an alarm unit or the like, although not shown in thedrawings.

The storage unit 180 may store a program for an operation of the controlunit 190, and temporarily store input/out data. The storage unit 160 mayinclude at least one of a flash memory type storage medium, a hard disktype storage medium, a multimedia card micro type storage medium, a cardtype memory (for example, a secure digital (SD) or extreme Digital (XD)memory), a random access memory (RAM), a static random access memory(SRAM), a read-only memory (ROM), an electrically erasable programmableread-only memory (EEPROM), a programmable read-only memory (PROM), amagnetic memory, a magnetic disk and an optical disk.

The control unit 190 may control an overall operation of the mobilerobot 10 according to an embodiment of the present invention, and managea flow of information or data between respective components.

Accordingly, in terms of hardware, the control unit 190 may include atleast one processor including a central processing unit (CPU)/microprocessing unit (MPU) and an execution memory (e.g., a register and/orthe random access memory (RAM), and a bus (or internal cable) forinputting and outputting predetermined data.

In addition, in terms of software, the control unit 190 may include apredetermined program routine and/or program data loaded into theexecution memory from a predetermined recording medium and processed bythe processor to perform various operations and functions of the mobilerobot 10 according to an embodiment of the present invention.

In addition, for example, in more detail, the control unit 190 maycontrol all or part of the driving unit 110, the rotating members 12 a,12 b and 12 c, the power supply unit 120, the input unit 130, theobstacle detection unit 140, the load detection unit 150, the directiondetection unit 151, the communication unit 160, the output unit 170 andthe storage unit 180.

Meanwhile, although not shown in the drawings, the mobile robot 10according to an embodiment of the present invention may include a watersupply unit for supplying a liquid (e.g., water or washing liquid) to atleast one of the first, second and third cleaners 13 a, 13 b and 13 c.

The control unit 190 may supply liquid to at least one of the first,second and third cleaners 13 a, 13 b and 13 c by controlling the watersupply unit.

The mobile robot 10 according to an embodiment of the present inventionmay perform the wet cleaning by using at least one of the first, secondand third cleaners 13 a, 13 b and 13 c, to which liquid is supplied fromthe water supply unit.

In addition, the mobile robot 10 according to an embodiment of thepresent invention may perform the dry cleaning by using the other of thefirst, second and third cleaners 13 a, 13 b and 13 c, to which liquid isnot supplied.

The mobile robot 10 according to an embodiment of the present inventionmay also perform the dry cleaning in a case where liquid is supplied tonone of the first, second and third cleaners 13 a, 13 b and 13 c.

FIG. 4 is a front view of the mobile robot according to an embodiment ofthe present invention; and FIG. 5 is a cross-sectional view of themobile robot according to an embodiment of the present invention.

Referring to FIGS. 4 and 5 , a first rotation axis A1-A2 and a secondrotation axis B1-B2, respectively corresponding to the first and secondrotating members 12 a and 12 b, which may determine the travel speed andtravel direction of the mobile robot 10 according to an embodiment ofthe present invention, may each be inclined to have a predeterminedangle with respect to a central axis corresponding to a vertical axis ofthe mobile robot 10.

In this case, the first and second rotating members 12 a and 12 b, asshown in FIGS. 4 and 5 , may each be inclined downwardly outward withrespect to the central axis to have a predetermined angle with theground (i.e., the surface to be cleaned).

Here, a region positioned far from the central axis among regions of thefirst cleaner 13 a and the second cleaner 13 b, respectively fixed tothe first and second rotating members 12 a and 12 b, may be stronglyadhered to the surface to be cleaned than a region positioned closer tothe central axis.

That is, when the first and second rotating members 12 a and 12 brotate, the relative frictional force generated between the surface tobe cleaned and the first and second cleaners 13 a and 13 b may be largerat outskirts than at a center of the main body 11.

Here, the central axis corresponding to the vertical axis of the mobilerobot 10 may indicate a vertical axis with respect to the surface to becleaned of the mobile robot 10. For example, under the assumption thatthe mobile robot 10 performs the cleaning while traveling an X-Y planeformed by X and Y axes during a cleaning operation, the central axis mayindicate a Z axis, which is the vertical axis with respect to thesurface to be cleaned.

In addition, the predetermined angle may include a first angle (degree“a”) corresponding to an angle at which the first rotation axis A1-A2 isinclined with respect to the central axis and a second angle (degree“b”) corresponding to an angle at which the second rotation axis B1-B2is inclined with respect to the central axis. Here, the first angle andthe second angle may be the same as or different from each other.

Meanwhile, referring to FIGS. 4 and 5 , a third rotation axis C1-C2corresponding to the third rotating member 12 c acting as asupplementary factor for the travel speed and travel direction of themobile robot 10 according to an embodiment of the present invention maybe parallel to the central axis corresponding to the vertical axis ofthe mobile robot 10, and the third rotating member 12 c may thus beparallel to the ground (i.e., the surface to be cleaned).

FIG. 6 is a flowchart showing a method for controlling a mobile robotaccording to another embodiment of the present invention. The method forcontrolling a mobile robot according to another embodiment of thepresent invention may be implemented in the mobile robot 10 according toan embodiment of the present invention described with reference to FIGS.1 to 5 . Hereinafter, the description describes the method forcontrolling a mobile robot according to another embodiment of thepresent invention and an operation of the mobile robot 10 forimplementing the method in detail with reference to the necessarydrawings.

Referring to FIG. 6 , the control unit 190 may select curved travel thatthe mobile robot 10 travels along a curved path [S100]. For example, auser may input a command including a cleaning mode in which the mobilerobot 10 travels along the curved path by using a remote controller (notshown). In addition, for example, the control unit 190 may select acleaning mode including a mode in which the mobile robot travels alongthe curved path among various cleaning modes by the user or by a presetalgorithm.

The S-shaped cleaning mode in which the mobile robot performs thecleaning while traveling in the S-shaped pattern, and the Y-shapedcleaning mode in which the mobile robot performs the cleaning whiletraveling in the Y-shaped pattern may be representative examples of thecleaning mode including the curved travel. It is obvious that the curvedtravel mentioned in the present specification is not limited to theS-shaped cleaning mode and the Y-shaped cleaning mode.

The mobile robot 10 may perform a combination of at least one of thestraight travel in which the mobile robot travels along the straightpath and the curved travel based on a specific cleaning mode or thepreset travel algorithm.

The curved travel may include the left or right forward travel along thecurved path and the left or right backward travel along the curved path.

For example, FIG. 7 is a view showing an example in which the mobilerobot moves forward to the left along a curved path according to anotherembodiment of the present invention; and FIG. 8 is a view showing anexample in which the mobile robot moves forward to the right along thecurved path according to another embodiment of the present invention.

In addition, for example, FIG. 9 is a view showing an example in whichthe mobile robot moves backward to the right along the curved pathaccording to another embodiment of the present invention. FIG. 10 is aview showing an example in which the mobile robot moves backward to theright along the curved path according to another embodiment of thepresent invention.

The control unit 190 may control the first and second driving units 110a and 110 b for the first and second rotating members 12 a and 12 b torotate at different speeds in opposite directions, based on a selectionof the curved travel in step S100 [S110].

In addition, the control unit 190 may control the third driving unit 110c for the third rotating member 12 c to rotate in the same direction asa rotation direction of a rotating member having a higher rotationalspeed among the first rotating member 12 a and the second rotatingmember 12 b [S120].

Here, the control unit 190 may control the third driving unit 110 c forthe third rotating member 12 c to rotate at a lower speed than therotating member having a higher rotational speed among the firstrotating member 12 a and the second rotating member 12 b.

In addition, the control unit 190 may control the driving unit 110 for arotational speed of the third rotating member 12 c to have a value of10% or more of the rotational speed of the rotating member having ahigher speed.

[Left Forward Curved Travel]

For example, referring to FIG. 7 , the mobile robot 10 may perform atravel mode in which the mobile robot moves forward along the curvedpath curved to the left.

First, in order to make the mobile robot 10 move forward, the controlunit 190 may control the first driving unit 110 a for the first rotatingmember 12 a to rotate in a counterclockwise direction, and may controlthe second driving unit 110 b for the second rotating member 12 b torotate in a clockwise direction.

Here, in order to make the mobile robot 10 move forward to the left, thecontrol unit 190 may control the first and second driving units 110 aand 110 b for the second rotating member 12 b to rotate at a higherspeed than the first rotating member 12 a.

In addition, in order for the mobile robot 10 to smoothly perform theleft forward curved travel, the control unit 190 may control the thirddriving unit 110 c for the third rotating member 12 c to rotate at alower rotational speed than the rotational speed to rotate at a lowerrotational speed than the second rotating member 12 b in the samedirection (i.e., the clockwise direction) as the second rotating member12 b′ of the second rotating member 12 b in the same direction (i.e.,the clockwise direction) as the rotation direction of the secondrotating member 12 b.

In addition, for example, referring to FIG. 8 , the mobile robot 10 mayperform the travel mode in which the mobile robot moves forward alongthe curved path curved to the right.

[Right Forward Curved Travel]

First, in order to make the mobile robot 10 move forward, the controlunit 190 may control the first driving unit 110 a for the first rotatingmember 12 a to rotate in the counterclockwise direction, and may controlthe second driving unit 110 b for the second rotating member 12 b torotate in the clockwise direction.

Here, in order to make the mobile robot 10 move forward to the right,the control unit 190 may control the first and second driving units 110a and 110 b for the first rotating member 12 a to rotate at a higherspeed than the second rotating member 12 b.

In addition, in order for the mobile robot 10 to smoothly perform theleft forward curved travel, the control unit 190 may control the thirddriving unit 110 c for the third rotating member 12 c to rotate at alower rotational speed than the rotational speed of the first rotatingmember 12 a in the same direction (i.e., the counterclockwise direction)as the rotation direction of the first rotating member 12 a.

[Right Backward Curved Travel]

In addition, for example, referring to FIG. 9 , the mobile robot 10 mayperform the travel mode in which the mobile robot moves backward alongthe curved path curved to the right.

First, in order to make the mobile robot 10 move backward, the controlunit 190 may control the first driving unit 110 a for the first rotatingmember 12 a to rotate in the clockwise direction, and may control thesecond driving unit 110 b for the second rotating member 12 b to rotatein the counterclockwise direction.

Here, in order to make the mobile robot 10 move backward to the right,the control unit 190 may control the first and second driving units 110a and 110 b for the first rotating member 12 a to rotate at the higherspeed than the second rotating member 12 b.

In addition, in order for the mobile robot 10 to smoothly perform theright backward curved travel, the control unit 190 may control the thirddriving unit 110 c for the third rotating member 12 c to rotate at thelower rotational speed than the rotational speed of the first rotatingmember 12 a in the same direction (i.e., the clockwise direction) as therotation direction of the first rotating member 12 a.

[Left Backward Curved Travel]

In addition, for example, referring to FIG. 10 , the mobile robot 10 mayperform the travel mode in which the mobile robot moves backward alongthe curved path curved to the right.

First, in order to make the mobile robot 10 move backward, the controlunit 190 may control the first driving unit 110 a for the first rotatingmember 12 a to rotate in the clockwise direction, and may control thesecond driving unit 110 b for the second rotating member 12 b to rotatein the counterclockwise direction.

Here, in order to make the mobile robot 10 move backward to the left,the control unit 190 may control the first and second driving units 110a and 110 b for the second rotating member 12 b to rotate at the higherspeed than the first rotating member 12 a.

In addition, in order for the mobile robot 10 to smoothly perform theleft backward curved travel, the control unit 190 may control the thirddriving unit 110 c for the third rotating member 12 c to rotate at thelower rotational speed than the rotational speed of the second rotatingmember 12 b in the same direction (i.e., the counterclockwise direction)as the rotation direction of the second rotating member 12 b.

Meanwhile, the rotational speed of the third rotating member 12 c maypreferably have a value of 30% or more of the rotational speed of therotating member having a higher rotational speed among the first andsecond rotating members 12 a and 12 b.

Meanwhile, for example, when the load on the floor surface is not higherthan a preset reference, the rotational speed of the third rotatingmember 12 c may have a value in a range of 50% to 80% of the rotationalspeed of the rotating member having a higher speed among the first andsecond rotating members 12 a and 12 b.

In addition, for example, when the load on the floor surface is higherthan the preset reference, the rotational speed of the third rotatingmember 12 c may have a value in a range of 50% to 100% of the rotationalspeed of the rotating member having a higher speed among the first andsecond rotating members 12 a and 12 b.

In addition, for example, when the mobile robot 10 performs the wetcleaning as described above, the rotational speed of the third rotatingmember 12 c may have the value in the range of 50% to 100% of therotational speed of the rotating member having a higher speed among thefirst and second rotating members 12 a and 12 b.

In addition, for example, when the mobile robot 10 performs the drycleaning as described above, the rotational speed of the third rotatingmember 12 c may have a value of 30% or more of the rotational speed ofthe rotating member having a higher speed among the first and secondrotating members 12 a and 12 b.

In this way, the control unit 190 may consider at least one of the loadon the floor surface (i.e., a friction level of the floor surface) andwhether the cleaner is wet or dry to determine the rotational speed ofthe first rotating member 12 a and the rotational speed of the secondrotating member 12 b, and a relative level of the rotational speed ofthe third rotating member 12 c with respect to the rotational speed ofthe first rotating member 12 a and the rotational speed of the secondrotating member 12 b.

The rotational speed of the first rotating member 12 a, the rotationalspeed of the second rotating member 12 b, the rotational speed of thethird rotating member 12 c and each relative speed level, based on atleast one of the load on the floor surface and whether the cleaner iswet or dry, may be stored in the storage unit 180 as a preset table oralgorithm, based on the travel mode, and invoked by the control unit 190when necessary.

Hereinafter, the description describes a method for controlling themobile robot 10 to maintain a preset curved path in detail withreference to FIG. 9 in a case where the mobile robot 10 according to anembodiment of the present invention deviates from the preset curved pathor the loads each applied to the first and second rotating members 12 aand 12 b are different from each other while the mobile robot travelsforward or backward to the left or right along the preset curved path.

FIG. 11 is a flowchart showing a method for controlling a mobile robotaccording to yet another embodiment of the present invention. The methodfor controlling a mobile robot according to yet another embodiment ofthe present invention may be implemented in the mobile robot 10according to an embodiment of the present invention described withreference to FIGS. 1 to 5 . Hereinafter, the description describes themethod for controlling a mobile robot according to yet anotherembodiment of the present invention and an operation of the mobile robot10 for implementing the method in detail with reference to the necessarydrawings.

Referring to FIG. 11 , the control unit 190 may detect the curved traveldirection or travel angle of the mobile robot 10 during the travel ofthe mobile robot 10 [S200].

Step S200 may be performed using a signal output from theabove-described direction detection unit 151.

As described above with reference to FIGS. 6 to 10 , the mobile robot 10may travel along the preset curved travel path. The preset curved travelpath may include at least one of the curved travel direction and thetravel angle.

The travel angle may indicate an angle related to a curvature formedwhen the mobile robot 10 moves forward or backward to the left or rightwhile forming a curve.

The control unit 190 may control the rotational speed of at least one ofthe first, second and third rotating members 12 a, 12 b and 12 c inconsideration of the curved travel direction or travel angle detected byexecution of step S200 for the mobile robot 10 to maintain the presetcurved travel direction or travel angle in a case where the mobile robotdeviates from the preset curved travel direction or travel angle [S210].

FIG. 12 is a flowchart showing a method for controlling a mobile robotaccording to still another embodiment of the present invention. Themethod for controlling a mobile robot according to still anotherembodiment of the present invention may be implemented in the mobilerobot 10 according to an embodiment of the present invention describedwith reference to FIGS. 1 to 5 . Hereinafter, the description describesthe method for controlling a mobile robot according to still anotherembodiment of the present invention and an operation of the mobile robot10 for implementing the method in detail with reference to the necessarydrawings.

Referring to FIG. 12 , the control unit 190 may detect at least one ofthe friction level of the floor surface and whether the cleaner is wetor dry during the travel of the mobile robot 10 [S300].

For example, the control unit 190 may determine the friction levels ofthe floor surface corresponding to the first rotating member and thefloor surface corresponding to the second rotating member by controllingthe load detection unit 150 to obtain the first load value applied tothe first rotating member 12 a and the second load value applied to thesecond rotating member 12 b.

In addition, for example, the control unit 190 may detect whether thecleaner is wet or dry by a signal received from an external remotecontroller or detection of a predetermined color corresponding to eachof the wet cleaner and the dry cleaner.

The control unit 190 may control the rotational speed of at least one ofthe first, second and third rotating members 12 a, 12 b and 12 c inconsideration of a detection result of step S300 for the mobile robot 10to travel while maintaining the preset curved travel path [S310].

As described above, the preset curved travel path may include at leastone of the curved travel direction and the travel angle.

For example, the control unit 190 may control the rotational speed of atleast one of the first and second rotating members 12 a and 12 b) inconsideration of the first load value and the second load value,obtained by the load detection unit 150, for the mobile robot 10 tomaintain the preset curved travel direction or travel angle with respectto a forward or backward direction.

For example, when the first load value is greater than a reference valueor the second load value in FIG. 7 , the mobile robot 10 may deviatefrom the preset curved path (i.e., arrow path shown in FIG. 7 ) andtravel while being curved further to the left than the arrow path shownin FIG. 7 .

Here in FIG. 7 , the control unit 190 may control the first driving unit110 a to increase the rotational speed of the first rotating member 12a. However, the control unit 190 is unable to increase the rotationalspeed of the first rotating member 12 a to be higher than the rotationalspeed of the second rotating member 12 b in order for the mobile robotto maintain its travel along the curved path (i.e. arrow path) shown inFIG. 7 .

In addition, for example, when the first load value is greater than thereference value or the second load value in FIG. 9 , the mobile robot 10may deviate from the preset curved path (i.e., arrow path shown in FIG.9 ) and travel while being curved further to the left than the arrowpath shown in FIG. 9 .

Here in FIG. 9 , the control unit 190 may control the first driving unit110 a to increase the rotational speed of the first rotating member 12a.

The methods for controlling a mobile robot according to variousembodiments of the present invention described above may be implementedby programs and provided to a server or devices. Therefore, eachapparatus may access the server or the device storing the program todownload the program.

In addition, the method for controlling a mobile robot according tovarious embodiments of the present invention described above may beimplemented by programs, and stored and provided in variousnon-transitory computer readable media. The non-transitory computerreadable medium is not a medium that temporarily stores data, such as aregister, a cache, a memory or the like, and indicates a medium thatsemi-permanently stores data and is readable by an apparatus. In detail,the various applications or programs described above may be stored andprovided in the non-transitory computer readable medium such as acompact disk (CD), a digital versatile disk (DVD), a hard disk, aBlu-ray disk, a universal serial bus (USB), a memory card, the read onlymemory (ROM) or the like.

Meanwhile, the functions of the various elements shown in the drawingsof the present invention may be provided through use of dedicatedhardware as well as hardware capable of executing software in relationto appropriate software.

Further, explicit use of the term “control unit” should not be construedas exclusively referring to the hardware capable of executing software,and may implicitly include, without limitation, a microprocessor (MCU),the digital signal processor (DSP) hardware, the read-only memory (ROM)to store the software, the random access memory (RAM) and thenon-volatile memory.

In the claims of the present specification, an element represented as ameans for performing a specific function encompasses any manner ofperforming the specific function, and this element may include any formof software, including a combination of circuit elements that performthe specific function or firmware, microcode or the like, combined withappropriate circuitry for executing software to perform the specificfunctions.

In the present specification, an expression ‘an embodiment’ of theprinciples of the present invention or the like, and variousmodifications of this expression are related to the correspondingembodiment and indicate that specific features, structures,characteristics or the like are included in at least one embodiment ofthe principles of the present invention.

Accordingly, the expression ‘an embodiment’ and any other modifiedexamples throughout the present specification may not denote the sameembodiment.

In a case where it is described in the present specification that amethod includes a series of steps, a sequence of these steps suggestedherein is not necessarily a sequence in which these steps may beexecuted. That is, any described step may be omitted and/or any otherstep that is not described herein may be added to the method.

In addition, unless explicitly described to the contrary, a singularform includes a plural form in the present specification. In addition, acomponent, step, operation and element, mentioned by terms ‘include’ or‘including’ used in the present specification and may indicate thepresence or addition of one or more other components, steps, operations,elements and devices.

Hereinabove, the description mainly describes the preferred embodimentsof the present invention. All embodiments and conditional illustrationsdisclosed in the present specification have been described to intend toassist in the understanding of the principle and concept of the presentinvention by those skilled in the art to which the present inventionpertains. Therefore, it will be understood by those skilled in the artthat the present invention may be implemented in modified forms withoutdeparting from the spirit and scope of the present invention. Therefore,the embodiments disclosed herein should be considered in an illustrativeaspect rather than a restrictive aspect.

The scope of the present invention should be defined by the claimsrather than the above-mentioned description, and equivalents to theclaims should be interpreted to fall within the present invention.

1. A mobile robot comprising: a main body; a driving unit installed onthe main body and supplying power for travel of the mobile robot; afirst rotating member, a second rotating member and a third rotatingmember, capable of accommodating respective cleaners and providingmovement power sources for the travel of the mobile robot by performingrespective rotational motions about a first rotation axis, a secondrotation axis and a third rotation axis by power of the driving unit;and a control unit controlling the driving unit for the first rotatingmember and the second rotating member to rotate at different speeds inopposite directions and for the third rotating member to rotate in thesame direction as a rotation direction of a rotating member having ahigher speed among the first rotating member and the second rotatingmember, wherein the first rotation axis corresponding to the firstrotating member and the second rotation axis corresponding to the secondrotating member are each inclined to have a predetermined angle withrespect to a central axis, corresponding to a vertical axis of themobile robot, for the first rotating member and the second rotatingmember to each have an angle with the ground, and the third rotationaxis corresponding to the third rotating member is parallel to thecentral axis for the third rotating member to be parallel to the ground.2. The mobile robot of claim 1, wherein the first, second and thirdrotation axes are formed for the first, second and third rotatingmembers to be disposed adjacent to one another.
 3. The mobile robot ofclaim 1, wherein the control unit controls the driving unit for thethird rotating member to rotate at a lower speed than the rotatingmember having a higher speed and for a rotational speed of the thirdrotating member to have a value of 10% or more of a rotational speed ofthe rotating member having a higher speed.
 4. The mobile robot of claim3, wherein the control unit controls the rotational speed of at leastone of the first, second and third rotating members for the mobile robotto maintain a preset curved travel direction or travel angle withrespect to a forward or backward direction during the travel of themobile robot.
 5. The mobile robot of claim 4, further comprising adetection unit capable of detecting the preset curved travel directionor travel angle, wherein the control unit controls the rotational speedof at least one of the first, second and third rotating members for atravel direction of the mobile robot to maintain the preset traveldirection or travel angle based on a signal of the detection unit in acase where the travel direction of the mobile robot deviates from thepreset curved travel direction or travel angle.
 6. The mobile robot ofclaim 5, wherein the detection unit includes at least one of anacceleration sensor and a gyro sensor.
 7. The mobile robot of claim 3,wherein the control unit controls the rotational speed of at least oneof the first, second and third rotating members in consideration of atleast one of a friction level of a floor surface on which the mobilerobot travels and whether the cleaner is wet or dry during the travel ofthe mobile robot.
 8. The mobile robot of claim 7, wherein the controlunit determines the friction levels of the floor surface correspondingto the first rotating member and the floor surface corresponding to thesecond rotating member by obtaining a first load value applied to thefirst rotating member and a second load value applied to the secondrotating member.
 9. The mobile robot of claim 8, wherein the controlunit controls the rotational speed of at least one of the first rotatingmember and the second rotating member in consideration of the first loadvalue and the second load value for the mobile robot to maintain apreset curved travel direction or travel angle with respect to a forwardor backward direction.
 10. The mobile robot of claim 7, wherein thecontrol unit determines whether the cleaner is wet or dry by any one ofa signal received from an external remote controller and detection of apredetermined color corresponding to each of the wet cleaner and the drycleaner.
 11. A method for controlling a mobile robot using rotationalforces of a plurality of rotating members as movement power sources forits travel, the method comprising: allowing a mobile robot to travel byrotating at least one of a first rotating member, a second rotatingmember and a third rotating member, capable of accommodating respectivecleaners and performing respective rotational motions about a firstrotation axis, a second rotation axis and a third rotation axis; andcontrolling the first, second and third rotating members for the firstrotating member and the second rotating member to rotate at differentspeeds in opposite directions and for the third rotating member torotate in the same direction as a rotation direction of a rotatingmember having a higher speed among the first rotating member and thesecond rotating member, wherein the first rotation axis corresponding tothe first rotating member and the second rotation axis corresponding tothe second rotating member are each inclined to have a predeterminedangle with respect to a central axis, corresponding to a vertical axisof the mobile robot, for the first rotating member and the secondrotating member to each have an angle with the ground, and the thirdrotation axis corresponding to the third rotating member is parallel tothe central axis for the third rotating member to be parallel to theground.
 12. The method of claim 11, wherein the first, second and thirdrotating members are disposed adjacent to one another.
 13. The method ofclaim 12, wherein the controlling includes controlling at least one ofthe first, second and third rotating members for the third rotatingmember to rotate at a lower speed than the rotating member having ahigher speed and for a rotational speed of the third rotating member tohave a value of 10% or more of a rotational speed of the rotating memberhaving a higher speed.
 14. The method of claim 13, further comprisingcontrolling the rotational speed of at least one of the first, secondand third rotating members for the mobile robot to maintain a presetcurved travel direction or travel angle with respect to a forward orbackward direction during the travel of the mobile robot.
 15. The methodof claim 13, further comprising: obtaining a first load value applied tothe first rotating member and a second load value applied to the secondrotating member during the travel of the mobile robot; and controllingthe rotational speed of at least one of the first rotating member andthe second rotating member in consideration of the first load value andthe second load value for the mobile robot to maintain a preset curvedtravel direction or travel angle with respect to a forward direction.16. The method of claim 13, wherein the controlling includes controllingthe rotational speed of at least one of the first, second and thirdrotating members in consideration of at least one of a friction level ofa floor surface on which the mobile robot travels and whether thecleaner is wet or dry during the travel of the mobile robot.
 17. Acomputer program stored in a medium to execute the method of claim 11 byusing a computer.
 18. A distribution server for distributing thecomputer program of claim
 17. 19. The mobile robot of claim 2, whereinthe control unit controls the driving unit for the third rotating memberto rotate at a lower speed than the rotating member having a higherspeed and for a rotational speed of the third rotating member to have avalue of 10% or more of a rotational speed of the rotating member havinga higher speed.